


A Blade of Silver, a Sickle of Ice

by Island_of_Reil



Category: Shingeki no Kyojin | Attack on Titan
Genre: Alternate Universe - Canon, Ass Play, Assassins & Hitmen, Blow Jobs, Cunnilingus, Doggy Style, F/M, Half-Sibling Incest, Twincest
Language: English
Status: Completed
Published: 2017-06-27
Updated: 2017-06-27
Packaged: 2018-11-19 18:08:22
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,204
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11318811
Author URL: https://archiveofourown.org/users/Island_of_Reil/pseuds/Island_of_Reil
Summary: They haven’t done badly for the twin get of an Underground whore, she often thinks. Nottruetwins, those of the same father as well as mother. Her eyes are proof of that. But born the same day, probably conceived the same night, clinging to one another in the womb as they cling to one another in the cold of the world outside it.





	A Blade of Silver, a Sickle of Ice

**Author's Note:**

> “ _I am a blade of silver, a sickle of ice._ Ghe sighed, intoning his old assasin’s mantra, hurtling across the space between two rooftops.”  
>  ― Greg Keyes, _The Blackgod_
> 
> This fic was inspired by [an FFA nonny](http://fail-fandomanon.dreamwidth.org/133571.html?thread=697352131#cmt69735) who has long wanted a Rivamika twincest assassin AU.

Mikasa stands on the ledge not far from the window, back flat against the bricks. Draped around her shoulders are two canister belts. Standing between her and the window are a pair of boots, smaller than her own.

She does not nervously fondle the hilt of the blade strapped to the outside of her right thigh, but her fingers rest lightly against its cool, smooth surface. It radiates reassurance, better than any prayer bead, better than anything against her skin except Levi.

Nothing moves on the ground below. The darkness is silent around her but for the summer sleighbells of crickets and the occasional fussing of a blackbird. And, just once, a muffled cry from the other side of the window, and then an even softer thud.

She raises her chin infinitesimally at these last sounds. They are followed by the soft plash of water being poured from an ewer into a bowl. Levi’s bare feet make no noise on the floor inside, they wouldn’t even if the window were open, but still she can sense him moving within. She could sense him, she would swear, if the two of them stood at the furthest opposite points within the Walls.

Sure enough, within a few seconds the casement eases slowly, silently open. Levi has scouted out the building and their target’s room therein on several previous occasions, and on at least two of them he made sure to oil the window hinges.

He slips out onto the ledge and reaches for his boots. As he lifts his right foot, the scant bow of the young moon briefly picks out the hilt of his own blade, snug in its sheath now against his right thigh. When Mikasa catches his eye, he gives her barely a nod, more a twitch of his head. It’s superfluous. She never assumes success at this point of a mission; nobody who is any good at what she and he do ever assumes they’ll leave the scene of a job alive and whole until they’re long gone. But she knows the answer from the one side of his face faintly lit by the moon, by the tensions in his frame and the tensions not in it.

She peels one belt from around her neck and hands it to him, and while he straps it back onto his hips she does the same with her own. And with a soft _hhwwisssh_ of gas they’re airborne, the wind lifting their hair, the relief of escape lifting their spirits. Later there will be gold, too. For now all that matters is that they succeeded and that his hand is warm in hers and that soon he will be warm against her and within her.

*

They haven’t done badly for the twin get of an Underground whore, she often thinks. Not _true_ twins, those of the same father as well as mother. Her eyes are proof of that. But born the same day, probably conceived the same night, clinging to one another in the womb as they cling to one another in the cold of the world outside it.

Mikasa would never say it out loud, especially not in front of Levi, but they have Kenny to thank for their fortune. A terrible man who imparted his terribleness to them, a crucial shield for two pretty and parentless children. Levi, she is sure, knows this too, even if he wouldn’t say it in front of her either.

They have Kenny to thank for their… arrangement as well, she suspects. If he’d never turned on his heel and walked away from them, would, that night, have Levi pulled her to him and put his face not in the crook of her shoulder but against her newly risen breasts? Would she in response have raked her hand down his chest and belly, hard as a man’s at fourteen, and continued to slide it down until a man’s hardness filled it?

Who knows. Maybe they would have done those things anyway, and once Kenny found out — and he would have found out — he’d have left them for it. He was a terrible man, and not just for his bloodstained hands; he wasn’t above punching them or throwing them into things when they failed him. But, though he might have been no prude, nor was he a pervert. More than that, he was always galled by their closeness, which never embraced him. She can imagine him catching them together, his ever-sour face roiling and contracting with a rare disgust. He’d have declared, _Fuck this. You brats were creepy to begin with. You wanna carry on like a couple of Western Rose inbreds, you can do it without me. I’m outta here._

Even Underground, after all, there remain lines that nobody crosses indifferently. 

*

So she and Levi have always been discreet. When they could afford better than shared body warmth on a pile of rags in an abandoned building, they bought separate pallets, just for show. These days, above the office in Trost out of which their front business is run, they keep separate bedrooms. That one of the two rooms goes unoccupied most nights is beside the point. They aren’t the only two people in that building, and talk spreads faster than plague.

Tonight, however, they’re headed to their other home, their truer home. They slip unseen below street level and glide silently along the Underground’s dark ceiling, far above the sputtering dirty-yellow lights below. They’re bound for the outskirts of the hidden city, for a squat and lightless iron rectangle half-sunk into the depths of the earth.

When the powers of Sina first carved out the Underground, the bunker housed soldiers and supplies. Before long, respectable humanity no longer ventured beneath the surface, and whatever the soldiers couldn’t take with them was soon stolen, repurposed, resold. Only the iron plates that made up the bunker’s walls and roof remained, too heavy and too solidly welded to be budged.

Levi and Mikasa didn’t buy the place; they commandeered it. They didn’t have to kill anyone, just drag out the squatters who didn’t resist beyond a few mumbled complaints and tell them to find a new place to get high and drool on themselves all day. Then, using metalwork tools for their original purposes for the first time in their lives, they took down one of the bunker’s walls. “Fresh air” is a relative term Underground, but what passes for it down there smells better than piss, shit, stale sweat, and the nasty industrial byproduct that’s smoked for a cheap high. They spent a few days cleaning the bunker thoroughly, camping alongside it by night, then put the iron plates back up and moved in.

The locks went on right after that. No lock can’t be picked, they know, and there’ll always be innocents and idiots who aren’t afraid of them. That’s what the booby traps are for. Levi takes a long kitchen match out of one of his leg pockets and strikes it against the side of his boot. Then he winds his adroit way around the traps, Mikasa following precisely in his footsteps. He passes her the match so that he can work the locks, some with keys, some with a hairpin. It’s good practice. She keeps those skills up too.

These days the bunker smells of bleach, cold iron, and the ashes of the last candle they burnt. Mikasa touches the match to a fresher candle on the little table by the door, then blows the match out. The small blaze sketches out the interior. The original sleeping quarters, working space, and storage room all flow into one another; only the shower and toilet area at left rear is closed off.

Other than the mirrors near the front door and in the shower area, plus a clock over the dining table, the only things on the walls are racks of weapons. Blades and firearms, mostly, with a few outliers like a spear and two bows, one long and one cross, with quivers of arrows. They have two larger tables, the wood of both gouged and splintered. One is round, with two permanent place settings, surrounded by several mismatched chairs. The other is rectangular, stacked with boxes of MREs “liberated” from the Garrison Legion and jugs of purified water, plus a few books. The one ironbound wooden chest contains ammunition and poisons and has a false bottom to conceal paperwork that can’t yet be burnt; it is heavily padlocked. The other chest is full of clothes and linens and is not locked at all. There’s also a metal cabinet full of cleaning and other household supplies, several tall tanks of 3DMG gas, and a brazier and sack of coal for colder nights.

And a pallet on the floor. A good-sized, well-stuffed, clean one. Just the one, with two pillows. There are, after all, no windows in the bunker.

*

Also on the floor as they walk in is a folded letter, centimeters from the door. They remove their boots and leave them alongside the wall, and Mikasa crouches to pick the letter up. Neither of them needs to observe that it’s from Isabel; she’s the only other person who knows their way around the booby traps.

It’s sealed with a blob of dirty wax, and the palimpsest has been scraped to hell and back. Mikasa squints at Isabel’s spidery, childlike hand, that of one who has come late to letters. Before Levi hauled her out of the gutter one day and brought her home, she hadn’t had anyone to teach her things. For good and for ill.

Mikasa gets through the first paragraph before she looks up to see Levi looking back expectantly at her. “She says someone sought her out to tell her about a man who might have some work for us,” she says. “The man’s name is Nicholas Lobov.”

Levi’s eyes flicker; he’s running the name through his head, listening for any bells that might ring. Apparently none do. “How is Isabel?” he asks.

“Doing okay,” Mikasa says, squinting at the palimpsest again. “Busy.” There are no details, of course. Isabel is not the brightest person Mikasa has ever met, but even the tiniest child of the Underground knows its number-one rule: keep your mouth shut.

When Mikasa looks up again, Levi’s mouth is slightly pinched. “And so is Farlan,” she adds, more softly, without being asked. Levi’s eyes go dead. But he doesn’t look away from Mikasa, because he never does.

“He’ll come around one day,” Mikasa says, like she always does. No cajoling, no hopeful tone, just a statement purporting to be fact.

“Yeah, maybe,” Levi mumbles, like he always does, and pushes his bangs off his forehead.

She will never tell him so, but Levi is closer to right than she is. She guesses that the rare occasions he hears Farlan’s name have that effect on him because he, too, will never forget Farlan’s expression when he first found out about them. He didn’t call them creepy or disgusting, as Kenny would have. But his face spoke volumes. He didn’t say he wanted nothing more to do with them. But they’ve only ever seen him in passing since.

She can live with that. Levi was much closer to Farlan than she was. And, until he found out what they are to one another, Farlan was hoping to get even closer than that. She will never tell Levi that, for her, his repudiation of them had a silver lining.

Mikasa sets the letter on what passes for their dining table. Levi is already unbuckling his 3DMG, which he sets down carefully on the other table. She can’t see his face, although she doubts it still reflects his chagrin over Farlan. Instead, she watches the play of his back muscles under his thin shirt. Then he grasps the hem and tugs it up, baring first the tender, kissable indentation at the small of his back; then the wide, strong plain in which his spine carves a deep valley; then his broad shoulders, the hard deltoids rounding out their squareness.

 _And nobody else gets to have it,_ she thinks. _Any of it._

She wants to reach out and, unbidden, run her finger up his spine. She does not, because his reflexes never sleep, even here, even with only her. Neither do hers. To relax them once is to step onto the path of carelessness, Kenny told them long ago.

Levi continues to undress, his trousers and underwear joining his shirt on the table. He is neither modest nor immodest about it, any more than if he were alone. Modesty is for abovegrounders. It doesn’t protect anyone else. Slavers don’t care how modest you are, and their days of dodging slavers are long over anyway.

Of course, he knows she’s watching. He won’t come to her now, not right after a job and before a shower. Mikasa wouldn’t mind; the night aboveground is relatively cool and they can’t have sweated that much. But she’s long since given up trying to convince him in such circumstances. Ritual, she’s come to understand, feels like a secure Gear wire to many people in a world without true safety. For some, it’s the Wall Church. For others, it’s a kiss to the hilt of their blade before battle. For Levi, it’s painstaking cleanliness.

“Gonna shower?” she asks.

“Yeah.”

He heads toward the rear of the bunker, the muscles in his ass rippling with his stride. She thinks of the illegal book that Armin, who runs their front business for them, has locked away in a safe in a hidden room in the building’s basement. He showed it to her once, when he was down there fixing a plumbing problem and she was helping him move heavy equipment. It has pictures of animals nobody is supposed to know about, and those include enormous, wild cats that live in hot places and can tear humans apart in seconds. Under their fur, they were solidly muscular. There was one with glossy black fur. It made her think of Levi. Whenever he’s naked and moving around, she thinks of that big cat.

The shower area door snicks shut, and now Mikasa’s got some time to kill. At least half an hour, maybe more. She doesn’t need a shower, but she guesses a quick wash wouldn’t hurt. She takes a few washcloths and a towel from the unlocked chest, a small basin and some kitchen soap from the cabinet, a jug of water from the table. Levi gives her shit about this habit she’s developed, wasting purified water instead of just hopping into the shower, but fuck it, she’d rather waste that than time she could be spending skin to skin with him. She’d shower _with_ him, but he doesn’t like company in there. She strips down with no more ceremony than he did, less actually, leaving all her clothes on the floor. Tepid water, plain soap, rough cloth — it’s good enough.

She drops the washcloths and towel on top of her clothes, then pads to the long table and picks up a book. The dust jacket is from a similarly sized book about the geology and climate of northern Wall Maria. The actual book beneath was an incidental find on a hit three years before, and highly illegal: the memoirs of a soldier who sabotaged enemy strongholds, back in the time when humanity fought against itself. Overkill for what she and Levi do, really, though they’ve gotten one or two minor tips out of it. She lent it to Armin, and when he returned it six months later he looked like he could’ve wept blood.

By the pallet, there’s a small box with a combination lock for a half-assed nightstand, and on it is a stout candle in a squat holder with a matchbook beside it. Mikasa lights it, then stretches out on top of the tightly made bedcover with the book. She’s rereading the chapter about planting explosives when the door in the rear opens again. Levi’s skin gleams in the light thrown by both candles, the dips and clefts between the muscles shadowy and sinuous as he moves. He frowns at the pile of clothes and towels on the floor, but immediately shelves his irritation; she can see him do it, behind his face, as though it were the kind of face people call “an open book.” They seldom argue, and when they do it’s not over petty shit.

“You should just give that to Armin for keeps,” he says.

“Maybe,” Mikasa says. She’s surprised at the resistance in her to that idea; she kind of likes rereading this book when she’s here and alone and bored, even if there’s nothing more to be gained from it. “While you’re up.” She holds it out to Levi, who puts it back onto the long table and returns to the bed.

He unfolds himself upon it. Mikasa thinks of a ladies’ fan, bone-white paper and glossy-black laqueur. Lying on her side, she runs two fingertips from his throat down his breastbone, the catch of his breath lifting his solid flesh to her touch. She continues downward a little, fingertips sliding between his abs, catching the fine sparse hairs of what passes for his treasure trail. His cock stirs, begins to fill, delicate pale pink deepening to rose.

“Can I do what I want?” she asks, her tone deceptively neutral.

Levi’s eyelids grow heavy, almost swell, and his pupils widen. “Why are you asking? Just do it.”

Mikasa swings her body over his, knees planted to either side, hands on his shoulders. Her head drops. His tongue is there at the touch of hers, wet, nimble, eager. When the kiss breaks, she looks him steadily in the eyes, ascertaining, reaffirming, as her fingertips press over and over against the formidable solidity of his deltoids.

The skin of his torso still tastes a little of soap. He likes to wash with an expensive soap that smells like fruit, but bright and biting, something that grows only in noblemen’s greenhouses. When she sucks a mark into his left pectoral, over his heart, she tastes more of him himself. Copper, mostly, like she was dipping her tongue into the blood flowing beneath his skin. She can feel his heart jump against her lips. She bites his nipples in turn; they swell hard and red against the crowns of her teeth. Levi’s breathing has picked up; he greets each bite with a quiet gasp.

When she looks up at his face, his eyes are three-quarters shut. “I told you to go ahead,” he says, breathless and faintly annoyed.

“I know,” Mikasa says. She doesn’t say _I want to look at your face._ He knows. Besides, it’d be cheesy.

She leaves soft, hot kisses all the way down him. He twitches beneath her, ticklish; she doesn’t linger on his abs but she likes how the light sensation takes him off guard, keys his nerves. He can take pain far better. She rubs her cheek against his pubic mound, the trimmed ends of the hair scratching her skin. He soaps up his pubes in the shower, but she can catch a flickering hint of musk in them anyway.

“The fuck are you doing?” Levi groans.

“What I want. You told me I could.”

He sighs and closes his eyes, unwilling to drop the mien of exasperation when, she guesses, someone else would be begging. They scrunch more tightly closed when she sucks the head of his cock into her mouth, though the only sound he makes is an intake of breath. 

She lets his cockhead rest in the lax embrace of her inner cheeks for a moment. He tastes of soap, clean musk, the coppery tang of his skin, and a bitter thread of pre-come. When she begins to ease it down her throat she takes her time, letting her muscles and breathing adjust. She trusts him from long experience not to face-fuck her, though when her lips reach his base his hips jerk involuntarily. Her hands on his hips, pressing him gently down against the pallet, remind him to control himself better. Under the touch he subsides to little more than his ragged breathing and his rosy flush and the throb and iron of his cock on her tongue.

She moves her right hand to his balls, testing their weight in her palm, teasing at the ridge on the underside. Levi arches his back, carefully, pushing them against her hand without ramming himself further down her throat. Mikasa’s fingertips drop lower and lower, stroking the delicate patch of skin behind them, eliciting the faintest of noises from him. She carefully considers his expression before sliding one fingertip to his hole, but she reasons that if he hadn’t used the water bulb tonight, he’d tell her to stop. He doesn’t.

After a moment of the soft, ruched flesh twitching under her stroke, she pulls off his cock and leans over again. In her peripheral vision she sees him open his eyes, but the annoyance in them is checked when he sees her move the candle from off the bedside box and deftly flick the number wheels. From the box’s interior she pulls out a tiny bottle of oil and uncorks it. The air around them fills with the scent of various flowers combined, as thick as a nobleman’s carpet.

“Priest lube,” Levi says tonelessly, eyes still shut.

“Yeah.”

The oil came from the far more expensive nightstand of a Wall Cult priest. All other trophies of that nature in his bedroom were left behind, at Levi’s insistence. _He shoved those things up his ass, Mikasa. We are_ not _taking them with us, for fuck’s sake._ She grins a little as she remembers the conversation while oiling up her fingers.

He takes two of them right away, up to the hilt. He squirms a little at the stretch and his breath hisses in, but there’s no real resistance in his ass to speak of. He squirms more and grunts when she rubs at the little knob in there. It has a name, it’s in one of those medical books their friend Eren inherited from his dad, but it’s really unsexy and she doesn’t like to remember it. “Harder,” he says raspily. She obliges with a steady, rubbing pressure and watches his hips rise off the bed and his cock flail around. _“Fuck,”_ he mutters. There’s a thin sheen of sweat breaking out over his forehead. He looks so pretty like this, even if the way his cock bounces looks silly.

She experiments with poking and tapping at the knob just as hard. She doesn’t want to damage anything in there, and while she wouldn’t call him a masochist he’s got way too high a pain tolerance — especially when he’s getting pleasure at the same time — for her to assume he’ll tell her to stop when she should. He starts making high-pitched sounds she thought he stopped being able to make when he hit puberty.

“You okay?” she asks.

“Yeah, yeah,” he wheezes, one corner of his mouth pulling down sourly. She’s overwhelmed with a rush of affection for a moment. “Don’t make me come though.”

“Okay,” she says, and goes back to prodding at the knob and watching him jerk around like a puppet and hearing him squeak. She considers adding a third finger but discards the idea because she’d rather play with his ass like this instead of fingerfuck him.

His pre-come is running freely and his balls are drawn up by the time he says, “Stop.” She pulls out her fingers. His eyes are hazy. “You wet at all?”

She checks. Her fingertip glides over plush-swollen membranes through thick fluid. “Mm,” she says.

“Gimme a taste.”

She runs the finger over his lips, which part to suck it in. His eyes are pretty much all pupil now. He pushes her fingertip back out of his mouth with his tongue and says hoarsely, “More.” She kneels astride him and knee-walks until she’s right over his face, then lowers her hips. He grabs them and goes to work.

He has every nerve in her cunt mapped out in his head, the same way both of them know the booby traps outside. At first he starts low, his tongue reaching out once or twice to touch the skin between her cunt and her asshole. It feels good, makes her start moving her hips a little, even if it doesn’t feel as good as him licking her clit. By the time he’s moved up to flick the tip of his tongue against the outer edge of the inner opening, she’s started to flow harder. Maybe every fourth breath she can hear him sucking a little of the wetness down his throat.

He doesn’t get to her clit tonight, though his tongue toys with the folds just around it as he slides a finger inside her. He presses the tip of it upward, not quite as hard as she did with him. She grunts rhythmically and begins to hump his face to the same rhythm. “Mmmph,” he says, pulling his finger out so he can hoist her into the air by both hips.

“Sorry,” she says breathlessly, looking down into his face.

“’Sfine. I wanna fuck you.”

As well as she knows him, it still always takes her a little by surprise how fast he moves when they’re in bed together. One second he’s on his back with almost her entire weight in his hands over his head. The next she’s grunting as her hands and knees hit the pallet, and his entire body is hard and warm against her back and ass and the backs of her widely spread thighs.

His cock is even harder and hotter, trapped at first between his body and the crease between her left ass cheek and left thigh. Then he lines it up with her cunt and pushes in. It’s her turn to squeak a little. She’s more than wet enough and she’s been taking him for years, but it’s so much tighter like this and he’s just pounding into her, their skin slap-slap-slapping together. He holds her in place with one arm around her torso, and the other hand is under her belly, finger moving as hard and fast as his cock is. She starts yelling now, low deep staccato yells, one for every prod of his fingertip into her clit. She’s already started to shove her ass backward against him, but with her fingers and toes digging into the bedcover for anchorage she can shove even harder.

 _“Fuck,”_ he hisses again, and then again, until it’s an obscene chant that picks up the rhythm of his thrusts and her counterthrusts and that counterpoints with her short sharp shouts. She’s really close, squeezing him hard enough to push him out and grinding so hard into his body she can feel the wiriness of his pubes against her ass cheeks. His thrusts are getting really short but hard enough now that if she weren’t anchored he could push her an inch forward on the pallet with each one. Then he gives her not his finger _tip_ but his finger _nail,_ just the edge of it skimming her clit, and her yell this time is long and guttural and she’s shaking like the ground under titan feet and the dark blue of the bedcover right in front of her face sizzles out to white.

In the delirium of coming she can hear his own graveled, filthy groan. Even when she can feel rivulets of come running out of her to stick in her pubes, he doesn’t stop driving into her or tweaking her clit right away. But the thrusts start losing their vigor, and when she makes an animal noise of discomfort from between her teeth he stops fondling her too. Both his arms are around her torso now, and she can feel the heat of his panting breath against her spine between her shoulder blades.

Finally both their breaths even out. Levi extricates his limp cock from Mikasa. Immediately, from long habit, she draws her knees together without otherwise changing position. She hears his feet hit the floor. He goes for one of the damp washcloths she left on top of her discarded clothes. Then she feels the rough nap against the backs of her thighs, which she parts again. She squirms at the feel of it on her hypersensitive cunt as he mops her up. He finishes, and she turns to sit on the pallet and watch him clean himself up. He grimaces a little himself at the feel of the washcloth.

He doesn’t come back to bed until he’s put both washcloths and her clothes atop his, then moved the entire pile to the non-dining table. These days, the time they used to spend wrestling with washtubs, harsh soap, buckets of water, and washboards is better spent on assignments, and they’re more than solvent enough to pay a laundress for her services. Mikasa doesn’t miss any of it, especially not how the soap would make her hands feel stiff and red even in the heat of summer.

When he returns he lies down alongside her, head on her shoulder, and her arm goes around his shoulders in turn. She remembers wishing, when were younger, that he’d grow taller than her. She used to wonder whether maybe it was her fault, if she should have always given him a portion of her food after they’d stolen it or bought it with stolen gold. After she’d realized, no, he was probably just the small son of a small father, it bugged her anyway. Weren’t they supposed to have become Big Brother, Little Sister, even if they were the same age?

Mikasa looks back at all that fretting now with a mental shake of her head. Within the bounds of his body, Levi contains so much, far more than just about anyone else she’s ever known. Only Armin comes close to that measure, and in a vastly different way.

He doesn’t say anything like _That was good._ He never does, and neither does she. They don’t have to; it’s pretty obvious, after all. Just like neither of them ever says _I love you_ either. She’s read, out of boredom, a few of novels in which people said those things to one another right after they fucked. Maybe they had to because they weren’t closely related. She guesses she sees the appeal, the reassurance, but she’d rather not say anything she doesn’t have to. The lack of necessity makes it more work than robbing or killing people is, in a weird kind of way. It’s not something she’d ever ask him about but her guess is he feels the same.

What he does say, muzzily, is “Eight hundred hours.”

“‘Kay,” she says, just as indistinctly. Meaning both of them will be blinking their eyes open at seven fifty-nine in the morning, without benefit of one of those wind-up clocks that rings until you can’t ignore it any longer and throw it across the room. They don’t say anything else until then.


End file.
